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Old Feb 08, 2013, 03:15 PM
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charlie eaton's Avatar
N.E.Mass.
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These formulas are all well and good however if you just set the power and look at what the boat is doing you can adjust to apparent speed. That is if it appears to look like it going at a scale speed it is and that is, as mentioned, what the set of the boat is in the water and what the wake appears to be. Keeping in mind that a PT boat at speed will look totally different with a load of torpedos and fuel(Does not plane) then it does empty(will plane). Basically just play with the trottle til it looks good.
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Old Feb 09, 2013, 05:28 AM
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Blackpool, Lancs
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When it looks right on the water, oddly enough, you find that the formula is being followed precisely. This works for displacement hulls, planing boats, yachts, cars, trains and planes, all at whatever scale. If it helps, just think of taking a 1:100 scale boat for a 1 mile walk round a lake. If the walk takes an hour, the boat will have looked like it was doing 10mph. The little man on the bridge, having done 1 real mile will have traveled 100 scale miles. Has he been doing 100mph? No, in your 1 hour he has just done a scale 10 hour trip.
If the prop was a perfect scale item, it would probably be rotating at full size times square root of scale. Just a thought, and justifying empirical results without resorting to Freaks constant or black magic.
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Old Feb 10, 2013, 10:36 AM
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Quote:
Originally Posted by mfr02 View Post
When it looks right on the water, oddly enough, you find that the formula is being followed precisely. This works for displacement hulls, planing boats, yachts, cars, trains and planes, all at whatever scale. ....
If the prop was a perfect scale item, it would probably be rotating at full size times square root of scale. Just a thought, and justifying empirical results without resorting to Freaks constant or black magic.

This is exactly what I want to achieve, I dont mind the WOT fun that comes with models. Just want to get her up on plane like the real thing and watch her glide for awhile.
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Old Feb 11, 2013, 05:08 AM
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Blackpool, Lancs
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If the hull form is right and it sits right, applying the right power will make it perform right.
The guesswork is knowing how efficient the props are compared to the real thing, what the losses are in the transmission, again, compared to the real thing, and remembering that while IC engines are rated by how much power they put out, electric motors tend to be rated by how much energy they take in. If the power of the original is known, converting horsepower to watts, scaling down and adding an extra 50% lands you in the right ball-park area.
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Old Feb 11, 2013, 09:19 AM
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United States, TX, Frisco
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Originally Posted by 4200burner View Post
Does anyone set their boat up for scale speed?
Nope, scale speed is too slow and unrealistic.

-R.
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Old Feb 11, 2013, 11:37 AM
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Vlaardingen, The Netherlands
Joined Nov 2008
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Quote:
Originally Posted by RICH404 View Post
Nope, scale speed is too slow and unrealistic.

-R.
As stated before, that is not the real scale speed for boats.
That is also not the way in which test tank facilities convert the data they gain from their models to full scale results.
The bow wave is the most important factor for what the actual scale speed is and that factor gives much more speed.

Greetings Josse
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Old Feb 11, 2013, 11:59 AM
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PDX, OR
Joined Dec 2002
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The Queen's Own Scale Model Warship Club ran scale speeds.
(to a point...)

The clubs Ship Scale was 1/72nd, and speeds were calculated so that any
model constructed would exhibit the advantage or disadvantage of its design and tonnage.

The slowest ships would be allowed to run a minimum 25 scale knots.
All other ships ran a calculated Scale speed. Our speed chart was as follows:
The scale speed of the vessel in second over 100 feet.

20 kts = 56.25
21 kts = 53.57
22 kts = 51.14
23 kts = 48.91
24 kts = 46.88
25 kts = 45.00
26 kts = 43.27
27 kts = 41.67
28 kts = 40.18
29 kts = 38.79
30 kts = 37.50
31 kts = 36.29
32 kts = 35.16
33 kts = 34.09
34 kts = 33.09
35 kts = 32.14
36 kts = 31.25
37 kts = 30.41
38 kts = 29.61
39 kts = 28.85
40 kts = 28.13
41 kts = 27.44
42 kts = 26.79
43 kts = 26.16
44 kts = 25.57
45 kts = 25.00
46 kts = 24.46
47 kts = 23.94
48 kts = 23.44
49 kts = 22.96
50 kts = 22.50
Watching a battle was kind of like watching the grass grow, but if
you were sailing a ship, then the timing and skill that it takes to create and
close a firing solution was challenging and fun. The ability to use a team mates
maneuvers to create a firing solution was evident in how you saw ships maneuver.
And you would also see ships maneuvering to create firing solutions for other team mates.

There is nothing so curious as to see three team mates standing yards apart at
the pond sailing destroyers and chasing a heavy cruiser,... watching one destroyer
turn into the cruiser to force a turn, and seeing two other destroyers synchronize
their turns to bring their guns to bear along the heavy cruisers projected course.
And none of them have said one word to each other during the maneuver.



Scale speeds feel very slow, but if all the ships are sailing at
proportional speed, then the scene they create can be very lovely.
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Old Feb 11, 2013, 07:47 PM
Fresh sea cucumber eater
JPCAT's Avatar
Joined Mar 2011
180 Posts
Our club also had the dispute of scale speed before. The conclusion was the speed which looks suitable for the ship. It is visual speed not numerical value.It is mainly based on the wave which the ship makes.
But it is not applied to springer. lol



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Old Feb 12, 2013, 12:01 PM
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Blackpool, Lancs
Joined Feb 2006
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Quote:
Scale speeds feel very slow, but if all the ships are sailing at
proportional speed, then the scene they create can be very lovely.
It will feel slow, the square root formula gives speeds approx twice the figures shown (i.e. half the number of seconds per 100 ft). But if everybody is working to the same rules, it doesn't really matter, especially if it looks good.
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